Non-sulfur yellow vulcanization system

In addition to the sulfur vulcanization system, most rubber manufacturers also have some non-sulfur vulcanization systems for both vulcanization of unsaturated rubber and vulcanization of saturated rubber, such as peroxides, metal oxides, phenolic resins, and terpenoids. Derivatives, maleimide derivatives, and the like. The vulcanization of unsaturated rubber with a non-sulfur vulcanization system can further improve the heat resistance of the rubber compound, while the fully saturated rubber must use a non-sulfur yellow vulcanization system.

Peroxide curing system

  • Application range

The peroxide can not only vulcanize saturated carbon chain rubber such as EPM, miscellaneous chain rubber such as Q, but also vulcanize unsaturated rubber, female mouth NR, BR, NBR, CR, SBR and the like. Compared with sulfur vulcanized vulcanizate, the crosslinked bond in the network structure of peroxide vulcanizate is CC bond, high bond energy, high heat, chemical stability, excellent resistance to thermal aging, and no vulcanization. Originally, vulcanizates have low compression set but poor dynamic properties. Static sealing rubber in static sealing or high temperature has a wide range of applications; some peroxides have odor, such as DCP, should be used when using.

  • Commonly used peroxide vulcanizing agents and vulcanizing agents

Commonly used peroxide vulcanizing agents are dialkyl peroxides, diacyl peroxides and peroxyesters, which can vulcanize most rubbers. The choice of peroxide generally requires consideration from the half-life of the peroxide, the volatility, the odor, the influence of the acid-base substance on it, the safety of the process, the physical and mechanical properties of the vulcanizate, and the like. Among them, dialkyl peroxides have been widely used, such as dicumyl peroxide (DCP), which is suitable for vulcanization at 160 ° C. It is cheap and is currently the most used vulcanizing agent; 1,1 – di-tert-butyl Oxy-3,3,5-trimethylcyclohexane (3M) suitable for lower temperature vulcanization.

  • Peroxide vulcanization mechanism

The crosslinking efficiency of a peroxide means the amount (mol) of a substance in which 1 mol of an organic peroxide causes chemical crosslinking of a rubber molecule. If 1 mol of peroxide can produce 1 mol of rubber crosslinks, the crosslinking efficiency is 1.

Peroxide vulcanization is the simultaneous generation of free radicals by peroxide under heat or radiation, such as alkyl peroxides to produce dialkoxy radicals, diacyl peroxides to produce two acyloxy radicals, and peroxyesters. An alkoxy radical and an acyloxy radical are produced. During thermal crosslinking, the tertiary alkyl and tertiary oxy radicals may be further cleaved to produce alkyl radicals.